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Corrosion in acids

One of the common ways of generating hydrogen in a laboratory is to place zinc into a dilute acid, such as hydrochloric or sulfuric. When this is done, there is a rapid reaction in which the zinc is attacked or dissolved and hydrogen is evolved as a gas (Fig. 2.8). This is shown inEqs. (2.10) to (2.14)  [Pg.31]

Equations (2.10) and (2.11) are the chemical shorthand for the following statement One zinc atom plus two hydrochloric acid molecules dissociate as ions and Cl and become one molecule of zinc chloride in Eq. (2.10) [written as a soluble salt in the form of Zn + and Cr ions in Eq. (2.11)] plus one molecule of hydrogen gas which is given off as indicated by the vertical arrow. It should be noted that the chloride ions do not participate directly in this reaction, although they could play an important role in real corrosion situations. [Pg.31]

Similarly, zinc combines with sulfuric add to form zinc sulfate (a salt) and hydrogen gas as shown in Eqs. (2.12) and (2.13)  [Pg.31]

Bubbling, or plating out of hydrogen on zinc immersed in a 0.1 M sulfuric acid solution. (Courtesy Kingston Technical Software) [Pg.31]

Note that each atom of a substance that appears on the left-hand side of these equations must also appear on the right-hand side. There are also some rules that denote in what proportion different atoms combine with each other. As in the preceding reaction, the sulfate ions that are an integral part of sulfuric acid do not participate directly to the corrosion attack and therefore one could write both Eqs. (2.11) and (2.13) in a simpler form  [Pg.32]


Chloride. Chloride is known to significantly increase the rate of corrosion in acidic fluoride media. The level of chloride that can be tolerated in the HF process before corrosion hinders plant operation is quite low. [Pg.196]

Corrosion (in acid solutions) At low potentials iron will be oxidised to Fe and Fe203 reduced to Fe, and the a-p will be > 10" g ion/1 water will be reduced to hydrogen or remain stable, depending upon whether E is below or above curve/. At high potentials iron will be oxidised to Fe and Fe203 will dissolve to form Fe (Ef i /f 2 = 0-76 V) water will be stable or will be oxidised to oxygen, depending upon whether E is below or above curve m, respectively. [Pg.67]

Copper additions appear to have the particular effect of reducing the corrosion stimulating effect of the sulphur content of an iron exposed to acid and the effect is thus less marked in low sulphur irons. Because sulphur can stimulate corrosion in acidic environments, it is usually kept as low as possible in irons to be used under these conditions. A low sulphur content is in any case metallurgically desirable. [Pg.588]

Tin anodes dissolve by etching corrosion in acid baths based on stannous salts, but in the alkaline stannate bath they undergo transpassive dissolution via an oxide film. In the latter the OH" ion is responsible for both film dissolution and for complexing the tin. Anodes must not be left idle because the film dissolves and thereafter corrosion produces the detrimental divalent stannite oxyanion. Anodes are introduced live at the start of deposition, and transpassive corrosion is established by observing the colour of the film... [Pg.348]

Thus, inhibitors of corrosion in acid solution can interact with metals and affect the corrosion reaction in a number of ways, some of which may occur... [Pg.812]

Corrosion or mixed potentials (a) Active corrosion in acid solutions (b) Passive metal in acid solutions Potential dependent on the redox potential of the solution and the kinetics of the anodic and cathodic reactions. Potential dependent on the kinetics of the h.e.r. on the bare metal surface. Potential is that of an oxide-hlmed metal, and is dependent on the redox potential of the solution. Zn in HCI Stainless steel in oxygenated H2SO4... [Pg.1242]

Fig. 11-2. Electron energy leveb for a mixed electrode reaction of iron corrosion in acidic solution = Fermi level of iron electrode Sfw/hj) = Fermi level of hydrogen redox... Fig. 11-2. Electron energy leveb for a mixed electrode reaction of iron corrosion in acidic solution = Fermi level of iron electrode Sfw/hj) = Fermi level of hydrogen redox...
The mechanism of steel corrosion in acid solutions, however, is different from that in neutral solutions in that the reduction reaction is the formation of hydrogen from hydrogen ion ... [Pg.78]

Because of this difference in corrosion mechanism in acid solution, the usefulness of the four evaluation techniques discussed above may be different than in neutral solutions. The purpose of this work was to evaluate these four techniques for predicting the behavior of coating resins in acid solutions. In addition, the ability of several different types of coating resins to protect steel against corrosion in acid solution was evaluated. [Pg.78]

Silicon-based materials (silicon carbide, silicon nitride) usually form a superficial film of silicon dioxide that protects the material against corrosion in acidic or neutral media. At pH equal to or higher than eleven it suffers corrosion heavily because the silicon dioxide is dissolved [25],... [Pg.518]

The reduction of strength after short time corrosion in acids (pit formation) cannot be correlated with the weight loss [511], whereas after intensive corrosion a correlation exists between thickness of the corroded layer and strength [507]. Acid corrosion appears to influence subcritical crack growth in Si3N4 ceramics [507, 523]. [Pg.126]

Fig. 12.6. The hydrogen-evolution reaction is the electronation reaction that occurs in zinc corrosion in acid solution. Fig. 12.6. The hydrogen-evolution reaction is the electronation reaction that occurs in zinc corrosion in acid solution.
In thinking about corrosion inhibition, it is implicitly assumed that one is dealing with a metal. This is fair enough in considering corrosion in acid solution, but the... [Pg.187]

Fig. 16.3. Evans diagram for metallic corrosion in acid medium. The concentrations are adjusted for eq to be equal for the three metals. Fig. 16.3. Evans diagram for metallic corrosion in acid medium. The concentrations are adjusted for eq to be equal for the three metals.
Swain G.M. The susceptibility to surface corrosion in acidic fluoride media - a comparison of diamond, HOPG and glassy carbon electrodes, J. Electrochem. Soc. (1994) 3382. [Pg.162]

Since the overpotential of cathodic proton reduction on metallic bismuth is relatively high, the metallic precipitate of bismuth makes the corrosion inhibited by decreasing the rate of the cathodic proton reduction and hence of the cathodic reaction of metallic corrosion in acid solution [87]. [Pg.581]

Figure 34.13 Oxygen corrosion in acid solution. (Adapted from K. J. Vetter, Electrochemical Kinetics. New York Academic Press, 1967, pp. 737-738.)... Figure 34.13 Oxygen corrosion in acid solution. (Adapted from K. J. Vetter, Electrochemical Kinetics. New York Academic Press, 1967, pp. 737-738.)...
Platinum was the initial choice for both the anodic and cathodic electrocatalysts for the following reasons (1) platinum shows minimum degradation or corrosion in acid or when used as an anodic or cathodic electrocatalyst (2) recent technical advances have been made in forming efficient high surface area porous platinum electrocatalyst structures at the surface of PEM membranes and (3) preliminary work... [Pg.2]

Although most corrosion systems can be described by the limiting models presented above, there are instances where control of the corrosion system is a combination of both types, viz., activation controlled anodic partial process with two cathodic partial processes - one under activation control and another under transport control. Examples are iron corrosion in acid solution with inorganic contaminants (, 18) and oxygen ( ). The corrosion current density in such systems is... [Pg.67]

There is another group of inhibitors which act by adsorption onto either the metal or the oxide. These are usually organic materials and the most effective are either alcohols or amines. They are mainly used in specialized applications such as inhibition of acid corrosion during pickling or in mitigation of corrosion in acid oil wells. The exact action of these inhibitors is beyond the scope of this chapter but they are discussed by Hackerman and others (14). Some buffering inhibitors, such as sodium benzoate may also act by adsorption on the surface. [Pg.147]

S. Bamartt, Tafel slopes for iron corrosion in acidic solutions. Corrosion 27 (1971) 467—470. [Pg.234]

N.K. AUam, Thermodynamic and quantum chemistry characterization of the adsorption of triazole derivatives during Muntz corrosion in acidic and neutral solutions, Appl. Surf. Sci. 253 (2007) 4570-4577. [Pg.444]

The results indicated that the pressure required for stopping tin corrosion decreases as the pH increases (Fig. E2.3). Extremely high pressure is required for pH = 1. Thus, increasing hydrogen pressure is not a feasible solution for stopping tin corrosion in acidic solutions. [Pg.641]

E.E. Oguzie, C.K. Enenebeaku, C.O. Akalezi, S.C. Okoro, A.A. Ayuk, E.N. Ejike (2010). Adsorption and corrosion-inhibiting effect of Dacryodis edulis extract on low-carbon-steel corrosion in acidic media. Journal of Colloid and Interface Science 349( 1), pp. 238-292. [Pg.428]

Popova, A. and Christov, M. Evaluation of impedance measurements on mild steel corrosion in acid media in the presence of heterocyclic compounds. Corrosion Science, 48(10),... [Pg.397]


See other pages where Corrosion in acids is mentioned: [Pg.147]    [Pg.123]    [Pg.813]    [Pg.881]    [Pg.47]    [Pg.147]    [Pg.127]    [Pg.262]    [Pg.351]    [Pg.211]    [Pg.1557]    [Pg.308]    [Pg.888]    [Pg.147]    [Pg.143]    [Pg.218]    [Pg.441]    [Pg.165]    [Pg.582]    [Pg.790]    [Pg.790]    [Pg.21]   
See also in sourсe #XX -- [ Pg.31 ]

See also in sourсe #XX -- [ Pg.515 ]




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Acid corrosion, 6.34

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